1. Field of the Invention
The invention is directed to a passive safety shield system associated with an injection pen needle.
2. Description of the Related Art
Accidental needlestick injuries from contaminated needles expose healthcare workers to the risk of infection from blood-borne pathogens, including the viruses that cause hepatitis B and C, and HIV. According to the Centers for Disease Control and Prevention, healthcare workers in the United States experience an estimated 600,000 exposures to blood each year, with RNs being subject to an overwhelming majority of these incidents.
While the injection device of choice in the U.S. remains the syringe, the demand for pen needles is growing rapidly. The use of self-injection injection pen devices is increasing due to the relative convenience, portability, and ease of use of these devices as compared to single use syringes. Pen needles are also becoming more commonplace in the hospital/clinical setting, as certain drugs, such as human growth hormone and osteoporosis medications, are available only in pen needle format.
Healthcare workers have sustained needlestick injuries while removing and disposing of needle hubs from pen needle devices after administering an injection to patients. The needles are typically removed after each injection to minimize contamination of the medication in the cartridge and to prevent needle re-use. Removal of the needle generally requires the re-shielding of the needle using the outer protective shield in which it was supplied and it is especially during the re-shielding step where injuries can occur. Needlestick injuries also occur during the removal of pen needles that have not been re-shielded.
U.S. Pat. No. 6,986,760 B2, assigned to the assignee of the present application, the disclosure of which is herein incorporated by reference in its entirety, teaches a pen needle and safety shield system wherein a safety shield, which normally encloses the needle cannula prior to use, permits retraction of the safety shield during injection and automatically extends and locks the shield in the extended enclosed position following use. The pen needle also prevents retraction of the shield during assembly of the shield and needle cannula and hub assembly on the pen injector.
U.S. Pat. No. 6,855,129 B2 discloses a safety needle assembly having a cylindrical housing with a needle mounted thereon for mounting onto a medical injection device. A shield is telescopically movable relative to the housing for movement between a distal position in which the shield covers the end of the needle, and a proximal position in which the needle is exposed. A spring located inside the housing urges the shield in the distal direction. A locking element on the device is provided inside the housing with outwardly pointing locking protrusions. The locking element is a separate part provided between the spring and the shield and it is longitudinally moved simultaneously with the shield relative to the housing during use, so that the protrusions on the locking element are guided from a first position where the shield is in the distal position, to a second position where the shield is in the proximal position, to a third position where the locking protrusions are blocked by a blocking surface provided on the inside surface of the housing, so that further movement of the shield is irreversibly immobilized.
However, the prior art does not disclose an injection pen needle having a non-injection end passive safety shield. The invention disclosed herein, which may be incorporated into prior art safety shielded pen needles, represents an advance in the art, at least in that novel means are provided to guard against accidental needlestick from the non-injection end of a needle in an injection pen needle.